On ultrastrong coupling in quantum Rabi theory

Li-Tuo Shen, Zhen‐Biao Yang, Mei Lu +2 more

Giuliano Benenti, Michele Stramacchia, G. Strini

The dynamical Casimir effect (DCE) manifests itself in the ultrastrong matter-field coupling (USC) regime, as a consequence of the nonadiabatic change of some parameters of a system. We show that the DCE is a fundamental limitation for standard quantum protocols based on quantum Rabi oscillations, implying that new schemes are required to implement high-fidelity ultrafast quantum gates. Our results are illustrated by means of a paradigmatic quantum communication protocol, i.e., quantum state transfer.

Maristella Crotti, Luca Razzoli, Luigi Giannelli +2 more

We investigate the open-system dynamics of a micromaser quantum battery in the ultrastrong-coupling (USC) regime. The battery consists of a quantized harmonic mode sequentially interacting, via the Rabi Hamiltonian, with a stream of qubits acting as chargers. USC enhances the charging speed but also induces unbounded energy growth and highly mixed cavity states. Dissipation suppresses this behavior, driving the system to a steady state with finite energy and ergotropy. Using optimal control theory, we show that the interplay between USC and dissipation enhances both charging performance and long-term stability against losses.

Anne Boutet de Monvel, Lech Zieliński

Jie Peng, Jianing Tang, Pinghua Tang +7 more

The authors demonstrate that certain solutions to the two-qubit quantum Rabi and Jaynes-Cummings models can be used to implement a high-quality deterministic single-photon source in the ultrastrong-coupling regime.

Jochen Braumüller, Michael Marthaler, Andre Schneider +4 more